Controller-Less Quick Tactile Feedback Keyboard

ABSTRACT

In some examples, techniques are provided for quick haptic feedback, without the use of a controller, which is local to individual, non-actuating keys, such as keys of a thin keyboard or keypad. The haptic feedback may be in the form of a simulated “key-click” feedback for an individual key that is pressed by a user such that the finger used to press the key feels the tactile sensation. The haptic feedback mimics the tactile sensation of a mechanical key (e.g., buckling spring, pop-dome key switch) to give a user the perception that they have actuated a mechanically movable key.

BACKGROUND

Keyboards are important and popular input mechanisms for providing inputto a variety of computing devices. Notwithstanding the development ofvarious alternative human input technologies, such as touchscreens,voice recognition, and gesture recognition, keyboards and keypads remainthe most commonly used device for human input to computing devices. Mosttrained typists who are able to type at moderate to high speeds (i.e.,about 50 words per minute or higher) tend to be reliant on hapticfeedback (i.e., touch or tactile feedback), which indicates to thetypist that a key has been depressed. Keyboards with mechanicallymovable keys (referred to herein as “mechanical keyboards”) havegenerally met this need by providing some form of naturally occurringhaptic feedback for a user who actuates these spring-loaded, movablekeys of the keyboard. For example, one popular mechanism used forproviding haptic feedback in traditional mechanical keyboards is a“buckling spring” mechanism underneath each key that buckles undersufficient pressure from a user's finger when the user actuates a key.The buckling of the spring causes a snapping action that provides atactile sensation to the user to indicate that the key has beenactuated.

As computing devices have become smaller and more portable with advancesin computer technology, the traditional mechanical keyboard has becomeless common, especially for computing devices with relatively small formfactors. This is because the technology used in mechanical keyboards mayprovide a design constraint on the maximum thinness of the keyboard.Manufacturers concerned with the portability of their devices haveaddressed this problem by developing alternative keyboard technologiesthat do not utilize mechanically movable keys. As a consequence, thesekeyboards with so called “non-actuating” keys may be made thinner andsleeker (˜3 millimeters thick) than even the thinnest mechanicalkeyboards. For example, pressure sensitive keyboards do not requiremechanically movable keys or parts. Thus, the main constraint on thethickness of a pressure sensitive keyboard is the material used for thecomponent layers of the keyboard providing structure and sensingfunctions. These alternative keyboard technologies have enabled moreportable computing devices and keyboards.

However, thinner keyboards with non-actuating keys (i.e., keys thatgenerally do not mechanically actuate) fail to provide tactile feedback.Typists who use such keyboards can only feel their finger on the surfaceof the key, but cannot feel any movement of the key. Without hapticfeedback, trained typists become unsure about whether a keystroke hasregistered, and they are forced to resort to visual feedback by checkingfinger placement, which slows down the typing speed.

SUMMARY

Described herein are techniques for providing quick haptic feedback,without the use of a controller that is local to individual,non-actuating keys, such as keys of a thin keyboard or keypad. Thehaptic feedback may be in the form of a simulated “key-click” feedbackfor an individual key that is pressed by a user such that the fingerused to press the key feels the tactile sensation. The haptic feedbackmimics the tactile sensation of a mechanical key (e.g., buckling spring,pop-dome key switch, etc.) to give a user the perception that they haveactuated a mechanically movable key.

This Summary is provided to introduce a selection of concepts in asimplified form that is further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Thesame reference numbers in different figures indicates similar oridentical items.

FIG. 1 illustrates an exploded, perspective view of an example actuatorswitch including a piezo actuator for localized haptic feedback.

FIG. 2A illustrates a partial side, cross-sectional view of the actuatorswitch along section line A-A of FIG. 1, including a flexible filmconfigured to flex in response to touch pressure.

FIG. 2B illustrates a partial side, cross-sectional view of the actuatorswitch along section line A-A of FIG. 1 after touch pressure is appliedto the flexible film causing the film electrode to contact the upperside piezo electrode.

FIG. 3 illustrates an exemplary computing device implementing theactuator switch.

FIG. 4 illustrates a block diagram for input detection for actuatorswitches of a keyboard.

FIG. 5 illustrates a block diagram for input detection for actuatorswitches of a keyboard.

FIG. 6 illustrates timing sequences for various actuator switches.

FIG. 7 illustrates an exploded, perspective view of an example actuatorswitch including a piezo actuator for localized haptic feedback.

FIG. 8A illustrates a partial side, cross-sectional view of the actuatorswitch along section line A-A of FIG. 7, including a flexible filmconfigured to flex in response to touch pressure.

FIG. 8B illustrates a partial side, cross-sectional view of the actuatorswitch along section line A-A of FIG. 7 after touch pressure is appliedto the flexible film causing the film electrode to contact the upperside piezo electrode.

FIG. 9 illustrates a block diagram of a keyboard encoder and actuatorswitches of the keyboard.

FIG. 10A illustrates a block diagram for input detection for an actuatorswitch.

FIG. 10B illustrates a block diagram for input detection for an actuatorswitch.

FIG. 10C illustrates a block diagram for input detection for an actuatorswitch.

FIG. 11 illustrates an exploded, perspective view of an example actuatorswitch that uses capacitive switching and includes a piezo actuator forlocalized haptic feedback.

FIG. 12A illustrates a partial side, cross-sectional view of theactuator switch along section line A-A of FIG. 11, including a flexiblefilm configured to flex in response to touch pressure.

FIG. 12B illustrates a partial side, cross-sectional view of theactuator switch along section line A-A of FIG. 11 after touch pressureis applied to the flexible film causing the film electrode to contactthe upper side piezo electrode.

FIG. 13A illustrates a block diagram for capacitive base key pushdetection.

FIG. 13B illustrates a block diagram for capacitive base key pushdetection.

FIG. 14 illustrates an exploded, perspective view of an example actuatorswitch including a piezo actuator for localized haptic feedback.

FIG. 15A illustrates a partial side, cross-sectional view of theactuator switch along section line A-A of FIG. 14, including a flexiblefilm configured to flex in response to touch pressure.

FIG. 15B illustrates a partial side, cross-sectional view of theactuator switch along section line A-A of FIG. 14 after touch pressureis applied to the flexible film.

FIG. 16 illustrates localized haptic feedback provided on a keyboardimplementing the haptic feedback assembly.

FIG. 17 is a flow diagram of an example process of providing hapticfeedback according to some implementations.

DETAILED DESCRIPTION

Embodiments of the present disclosure are directed to, among otherthings, techniques and systems for providing quick haptic feedbackwithout the use of a controller that is local to individual,non-actuating keys of a physical keyboard or keypad. As used herein, theterm “keyboard” may include any type of keyboard, keypad, or inputdevice suitable for including non-actuating keys. Embodiments disclosedherein find particular application to keyboards integrated with, or usedas a peripheral device to, slate or tablet computers, notebooks orlaptop computers, and the like. In particular, the embodiments disclosedherein benefit portable computing devices by providing a relatively thinkeyboard with improved portability that is also functional for a touchtypist. However, it is to be appreciated that the disclosed embodimentsmay also be utilized for other applications, including remote controlinput devices for television or similar devices, gaming systemcontrollers, mobile phones, automotive user input mechanisms, homeautomation (e.g., keyboards embedded in furniture, walls, etc.), and thelike.

The techniques and systems disclosed herein utilize a piezoelectricactuator (piezo actuator) as part of an actuator switch in a keyboardwith non-actuating keys. The piezo actuator deforms and alters shape inresponse to electrical current, which causes a tactile perception.Although a piezo actuator is described herein, any other type ofactuator may be used that generates a suitable physical response to anelectrical current for providing haptic feedback. A variety of naturaland synthetic materials exhibit the piezoelectric effect. Suitablematerials for piezo actuators include, but are not limited to, ceramicmaterials, crystal materials, and the like.

Multiple actuator switches may be positioned in a layout thatsubstantially corresponds to a layout of non-actuating keys of akeyboard. In some illustrative examples, the mechanical force producedby each actuator switch can be isolated and local to each non-actuatingkey of the keyboard. The haptic feedback can create a localized, tactilekey-click sensation on a user's finger that presses upon an individualnon-actuating key.

The techniques and systems described herein may be implemented in anumber of ways. Example implementations are provided below withreference to the following figures.

Example Actuator Switch

FIG. 1 illustrates an exploded, perspective view of an example actuatorswitch 100 including a piezo actuator 102 for localized haptic feedback.A piezo electrode 104 is on the top surface of the piezo actuator 102and a film electrode 106 is on a bottom surface of a flexible film 108.The bottom surface of the piezo actuator 102 is on a top surface of aconductive base plane 110, which may be made of copper or any othersuitable conductive material. The film electrode 106 is connected to ahigh voltage signal source (HVP). The base plane 110 is connected tosignal ground (SG). The piezo electrode 104 is connected to a highimpedance input detector (DT). Electrically conductive adhesive may beused to couple the piezo actuator 102 to the base plane 110. However,any suitable means of attaching the piezo actuator 102 to the base plane110 may be utilized, such as a latch or similar feature that fits over aside of the piezo actuator 102 to hold it in place.

A spacer 112 between the flexible film 108 and the base plane 110provides for a at least a threshold distance or gap (e.g., at least aminimum distance) to be maintained between the film electrode 106 andthe piezo electrode 104 when there is no touch pressure or less than athreshold amount (e.g., less than a maximum amount) of touch pressureexerted on the flexible film 108 above the film electrode 106. The filmelectrode 106 is located above the piezo electrode 104. The spacer 112has a hole to allow the film electrode 106 to contact the piezoelectrode 104 in response to touch pressure on the flexible film 108above the film electrode 106.

In some illustrative examples, the spacer 112 is configured to insulatethe flexible film 108 from the base plane 110. This spacer 112 can helpto prevent shorting an associated circuit, and can also providestructure to the actuator switch 100 by filling space in areas betweenthe flexible film 108 and the base plane 110. The spacer 112 may be anysuitable electrically insulating material, such as plastic, polymermaterial like polyethylene, glass, and the like.

Furthermore, FIG. 1 shows the piezo actuator 102 as being disc-shaped,but any suitable shape may be utilized. For example, the piezo actuator102 may be square, rectangular, or some other suitable shape, and may beof variable cross-section thickness or otherwise non-uniform in shape.The piezo actuator 102 can also be multi-layered.

FIG. 2A illustrates a partial side, cross-sectional view of the actuatorswitch 100 along section line A-A of FIG. 1, including the flexible film108 configured to flex in response to touch pressure. In the illustratedexample, the spacer 112 provides for a at least a threshold distance orgap 202 to be maintained between the film electrode 106 and the piezoelectrode 104 when there is no touch pressure exerted on the flexiblefilm 108 above the film electrode 106. For example, the gap 202 can beat least a sufficient distance that prevents film electrode 106 fromcontacting or creating an electrical connection with the piezo electrode104. The threshold distance can be the minimum distance necessary toprevent film electrode 106 from contacting or creating an electricalconnection with the piezo electrode 104. Thus, the spacer 112 ensuresthat the gap 202 is sufficiently large to prevent any electricalcoupling between the film electrode 106 and the piezo electrode 104 inthe absence of pressure exerted on the flexible film 108 or when lessthan a threshold amount (e.g., less than a maximum amount) of pressureis exerted on the flexible film 108.

FIG. 2B illustrates a partial side, cross-sectional view of the actuatorswitch along section line A-A of FIG. 1 after touch pressure is appliedto the flexible film 108 causing the film electrode 106 to contact thepiezo electrode 104. In the illustrated example, a finger 204 exerts atleast a threshold amount of pressure onto the flexible film 108 abovethe film electrode 106. The threshold amount of pressure can be theminimum amount of pressure that is sufficient to cause the filmelectrode 106 to contact the piezo electrode 104 through flexing of theflexible film 108. In response to the film electrode 106 contacting thepiezo electrode 104, the voltage on piezo electrode 104 can rise (e.g.,become “high voltage”), causing a key push to be detected by the highimpedance input detector. Also in response to the film electrode 106contacting the piezo electrode 104, the high voltage is applied to thepiezo actuator 102, causing the piezo actuator 102 to deform instantlyor approximately instantly. The deforming of the piezo actuator 102 cangenerate haptic and tactile feedback to the finger 204.

Since the key push can be detected at the same or approximately sametime as the deformation of the piezo actuator 102, there is little or nodelay from the detection of the key push to the generation of tactilefeedback. Thus, no controller circuit is needed for selecting anactuator and applying a signal. In some illustrative examples, surgeabsorbing devices are added to the input line of the high impedanceinput detector, such as a varistor or transient voltage suppressor(TVS), in order to prevent damage to the input detector (e.g., in theevent of excessive voltage spikes, such as voltage spikes caused bydeformation of piezo materials, power surges, etc.).

Example Computing Device

FIG. 3 illustrates an exemplary computing device implementing theactuator switch 100 of FIG. 1. The representative computing device 300may include one or more keyboards 302. The keyboard 302 may include oneor more of the actuator switches 100. In some illustrative examples, thekeyboard 302 may be peripheral to, or integrated within, any type ofcomputing device where touch-based typing input may be utilized. Forexample, the keyboard may be physically connected to such a computingdevice through electrical couplings such as wires, pins, connectors,etc., or the keyboard may be wirelessly connected to the computingdevice, such as via short-wave radio frequency (e.g., Bluetooth®), oranother suitable wireless communication protocol. Thus, the computingdevice 300 shown in FIG. 3 is only one illustrative example of acomputing device and is not intended to suggest any limitation as to thescope of use or functionality of the computing device. Neither shouldthe computing device 300 be interpreted as having any dependency norrequirement relating to any one or combination of components illustratedin FIG. 3.

In at least one configuration, the computing device 300 comprises one ormore processors 304 and computer-readable media 306. The computingdevice 300 may include one or more input devices 308, such as thekeyboard 302. The input device 308 may include the actuator switch ofany of the embodiments disclosed herein, such as the actuator switch 100of FIG. 1, the actuator switch 700 of FIG. 7, the actuator switch 1100of FIG. 11, or the actuator switch 1400 of FIG. 14. The input devices308 may also include, in addition to the keyboard 302, a mouse, a pen, avoice input device, a touch input device, etc.

The computing device 300 may include one or more output devices 310 suchas a display, speakers, printer, etc. coupled communicatively to theprocessor(s) 304 and the computer-readable media 306. The computingdevice 300 may also contain communications connection(s) 312 that allowthe computing device 300 to communicate with other computing devices 314such as via a network.

The computer-readable media 306 of the computing device 300 may store anoperating system 316, and may include program data 318. The program data318 may include processing software that is configured to processsignals received at the input devices 308, such as detection of akey-press event on the keyboard 302.

In some implementations, the processor 304 is a microprocessing unit(MPU), a central processing unit (CPU), or other processing unit orcomponent known in the art. Among other capabilities, the processor 304can be configured to fetch and execute computer-readableprocessor-accessible instructions stored in the computer-readable media306 or other computer-readable storage media. Communication connections312 allow the device to communicate with other computing devices, suchas over a network. These networks can include wired networks as well aswireless networks.

The one or more processors 304 may include a central processing unit(CPU), a graphics processing unit (GPU), a microprocessor, a digitalsignal processor, and so on. The computer-readable media 306 may beconfigured to store one or more software and/or firmware modules, whichare executable on the one or more processors 304 to implement variousfunctions. The term “module” is intended to represent example divisionsof the software for purposes of discussion, and is not intended torepresent any type of requirement or required method, manner ororganization. Accordingly, while various “modules” are discussed, theirfunctionality and/or similar functionality could be arranged differently(e.g., combined into a fewer number of modules, broken into a largernumber of modules, etc.).

Alternatively, or in addition, the functionally described herein can beperformed, at least in part, by one or more hardware logic components.For example, and without limitation, illustrative types of hardwarelogic components that can be used include field-programmable gate arrays(FPGAs), application-specific integrated circuits (ASICs),application-specific standard products (ASSPs), system-on-a-chip systems(SOCs), complex programmable logic devices (CPLDs), etc.

computer-readable media 306 includes tangible and/or physical forms ofmedia included in a device and/or hardware component that is part of adevice or external to a device, including but not limited torandom-access memory (RAM), static random-access memory (SRAM), dynamicrandom-access memory (DRAM), read-only memory (ROM), erasableprogrammable read-only memory (EPROM), electrically erasableprogrammable read-only memory (EEPROM), phase change memory (PRAM),flash memory, compact disc read-only memory (CD-ROM), digital versatiledisks (DVDs), optical cards or other optical storage media, magneticcassettes, magnetic tape, magnetic disk storage, magnetic cards or othermagnetic storage devices or media, solid-state memory devices, storagearrays, network attached storage, storage area networks, hosted computerstorage or any other storage memory, storage device, and/or storagemedium that can be used to store and maintain information for access bya computing device.

Although the computer-readable media 306 is depicted in FIG. 3 as asingle unit, the computer-readable media 306 (and all other memorydescribed herein) may include computer storage media or a combination ofcomputer storage media and other computer-readable media.Computer-readable media 306 may include computer storage media and/orcommunication media. Computer storage media includes volatile andnon-volatile, removable and non-removable media implemented in anymethod or technology for storage of information such ascomputer-readable instructions, data structures, program modules, orother data. Computer storage media includes, but is not limited to,phase change memory (PRAM), static random-access memory (SRAM), dynamicrandom-access memory (DRAM), other types of random-access memory (RAM),read-only memory (ROM), electrically erasable programmable read-onlymemory (EEPROM), flash memory or other memory technology, compact diskread-only memory (CD-ROM), digital versatile disks (DVD) or otheroptical storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other non-transmissionmedium that can be used to store information for access by a computingdevice.

In contrast, communication media may embody computer-readableinstructions, data structures, program modules, or other data in amodulated data signal, such as a carrier wave, or other transmissionmechanism. As defined herein, computer storage media does not includecommunication media.

Example Input Detection for a Keyboard

FIG. 4 illustrates a block diagram for input detection for actuatorswitches of a keyboard 302. In the illustrated example, the keyboard 302includes a plurality of actuator switches 402(1), 402(2), 402(3) . . .402(N). Each actuator switch 402 represents an example implementationfor the actuator switch 100 of FIG. 1. As an example, the actuatorswitch 402(N) can have a corresponding film electrode 404, asillustrated, and can be connected to a high voltage signal source 406. Arespective piezo electrode 408 opposite of the film electrodes 404 maybe connected to a corresponding piezo actuator 412, which may beconnected to a base plane 414, such as the base plane 110 of FIG. 1. Thebase plane 414 may be connected to a signal ground 416. One or more ofthe piezo electrodes 408 may also be connected to a high impedance inputdetector 410 via a respective input line 418 to the input detector 410.Surge protection can be improved by adding a surge absorbing device 420(e.g., varistor or TVS) to the one or more input lines 418 to the inputdetector 410. In the illustrated example, each of the plurality ofactuator switches 402(1), 402(2), 402(3) . . . 402(N) can include acorresponding film electrode 404, piezo electrode 408, piezo actuator412, input line 418, and surge absorbing device 420 in an arrangement asdiscussed above for the actuator switch 402(N).

FIG. 5 illustrates a block diagram for input detection for actuatorswitches of a keyboard 302. In the illustrated example, the keyboard 302includes a plurality of actuator switches 502(1), 502(2), 502(3) . . .502(N). Each actuator switch 502 represents an example implementationfor the actuator switch 100 of FIG. 1. As an example, the actuatorswitch 502(N), can have a corresponding film electrode 504, asillustrated, and can be connected to a high voltage signal source 506. Arespective piezo electrode 508 opposite of the film electrodes 504 maybe connected to a corresponding piezo actuator 510. Each of therespective piezo actuators 510 may be connected to a corresponding baseplane 512. The respective base planes 512 may be connected to acorresponding high impedance input detector 514 by a corresponding inputline 524. Each of the respective base planes 512 may also be connectedto a common base plane 516 via a corresponding resistor 518. Thus, thebase plane for each actuator switch may be separately connected to thecommon base plane 516. The common base plane 516 may be connected to asignal ground 520. The value of the resistors 518 may be selected toensure a logical “high” level for the input detector 514 when the highvoltage signal source 506 is applied to the piezo electrodes 508. Theillustrated example may allow for more efficient and inexpensivemanufacturing because input impedance of the input detector 514 can bereduced and no wiring to the piezo electrode 508 is needed. Surgeprotection can be improved by adding a surge absorbing device 522 (e.g.,varistor or TVS) to each of the input lines 524 of the input detector514. In the illustrated example, each of the plurality of actuatorswitches 502(1), 502(2), 502(3) . . . 502(N) can include a correspondingfilm electrode 504, piezo electrode 508, piezo actuator 510, base plane512, resistor 518, surge absorbing device 522, and input line 524 in anarrangement as discussed above for the actuator switch 502(N).

Example Timing Sequences of Actuator Switches

FIG. 6 illustrates timing sequences for various actuator switches. Avoltage signal 602 shows the voltage signal on the piezo electrode 104of FIG. 1 during various points in time. In the illustrative example,the voltage of the high voltage signal source (HVP) is constantly set to“vH,” which can be any voltage level suitable for use as a high voltagesignal level. When a key is not pressed (e.g., no touch pressure isapplied to the flexible film 108 above the piezo electrode 104), thevoltage on the piezo electrode may be zero or approximately zero. Whenat least a threshold of touch pressure is applied to the flexible film108 above the piezo electrode 104 that is sufficient to cause filmelectrode 106 to contact the piezo electrode 104 (e.g., a key is“pressed”), the film electrode 106 may contact the piezo electrode 104,which may cause the voltage signal 602 to quickly reach a value of “vH”within upward settling time of tAT 604 (the upward settling time isrepresented as “tAT”). The value of tAT 604 may depend on thecapacitance of the piezo actuator 102. The value of tAT 604 may berelatively short because of the small capacitance and high impedance ofthe piezo actuator 102 and the low impedance of the high voltage signalsource (HVP).

The instant or approximately instant voltage change may cause a quickdeformation of the piezo actuator 102, generating a “click” tactilefeedback to the finger 204. When the key is released (e.g., touchpressure is removed from the flexible film 108 above the piezo electrode104), the film electrode 106 may separate from the piezo electrode 104,so the high voltage signal is no longer applied to the piezo actuator102. In the illustrative example, the downward settling time tDK 606(the downward settling time is represented as “tDK”) is longer than tAT604 because the impedance of the piezo actuator 102 and the inputdetector is relatively high. Since tDK 606 is longer or substantiallylonger than tAT 604, no clear “click” feeling may be observed due toreleasing a key.

In another illustrative example, a voltage signal 610 shows the voltagesignal on the piezo electrode 104 of FIG. 1 during various points intime. The voltage signal 608 of the HVP may contain an eigen frequency“f0” of the piezo actuator 102 that can generate a relatively largedeformation of the piezo actuator 102. For example, the voltage signal608 of the HVP can mainly provide a high voltage DC signal of a voltagevalue “vH,” and the voltage signal 608 may have a short dip for each“1/f0” cycle. When a key is pressed (e.g., at least a minimum thresholdof touch pressure is applied to the flexible film 108 above the piezoelectrode 104), the film electrode 106 may contact the piezo electrode104, which may cause the voltage signal 610 on the piezo electrode 102to have a relatively short settling time of tAT 612. During the upwardsettling time of tAT 612, “f0” components may appear and enhance thedeformation of the piezo actuator 102, which can result in relativelylarger tactile and haptic feedback. After the upward settling time oftAT 612, the voltage signal 610 may arrive at a value of “vH,” which isthe voltage of the HVP, and the portion of the voltage signal 610 thatis due to the “f0” component of the voltage signal 608 may dissolve,dissipate, or reduce to a smaller or negligible amount. In someexamples, at this point, no tactile feedback is provided or observedbecause of the high impedance of the piezo actuator 102 and HVP's lowimpedance (and also because of the short duration of each dip of thevoltage signal 610). In other examples, a reduced tactile feedback isprovided because of the high impedance of the piezo actuator 102, HVP'slow impedance, and the short duration of each dip of the voltage signal610. The measured capacitance 614, the AC component 616 (alternatingcurrent component) of the measured capacitance 614, the measured voltage618 and the AC component 620 of the measured voltage 618 will bediscussed in more detail below with respect to FIGS. 11-15.

Example Actuator Switch

FIG. 7 illustrates an exploded, perspective view of an example actuatorswitch 700 including a piezo actuator 702 for localized haptic feedback.In the illustrative example, an actuator switch, similar to or the sameas the actuator switch of FIG. 1 is placed beneath an existing orordinary keyboard's base film 704. The film electrode 706, locatedbeneath a flexible film 708, may be aligned with a corresponding key top710 of a keyboard, such as the keyboard 302 (e.g., aligned with the “A”key or “enter” key). In the illustrative example, the key top 706 is atype of force sensing resistor. However, any other suitable type ofswitching-based mechanism may be used, such as a membrane, dome-switch,or capacitive switch. In the illustrative example, the film electrode706 is connected to a high voltage signal source (HVP) and a base plane712 is connected to HVP's ground (HVG). A piezo electrode 714 is alignedwith the film electrode 706 and is on a top surface of the piezoactuator 702. The key top 706 may also have electrodes that connect tothe keyboard 302's original encoder (to Rn and Cm, which are inputs tothe encoder). An example encoder is described in more detail below withregard to FIGS. 9 and 10. Furthermore, a spacer 716 is located betweenthe flexible film 708 and the base plane 712, similar to the spacer 112of the actuator switch 100 of FIG. 1.

FIG. 8A illustrates a partial side, cross-sectional view of the actuatorswitch 700 along section line A-A of FIG. 7, including the base film 704and the flexible film 708 configured to flex in response to touchpressure. In the illustrative example, the film electrode 706 is alignedwith the key top 710 of the keyboard 302. The spacer 716 maintains a gap802, similar to the spacer 112 of FIG. 1.

FIG. 8B illustrates a partial side, cross-sectional view of the actuatorswitch 700 along section line A-A of FIG. 7 after touch pressure isapplied to the key top 704 causing the film electrode to contact theupper side piezo electrode. In the illustrative example, at least aminimum threshold amount of touch pressure is applied by the finger 204to the key top 710, which causes the film electrode 706 to contact thepiezo electrode 714. Thus, both the base film 704 and the flexible film708 may bend to allow the electrodes to contact, which may cause thepiezo actuator 702 to generate a “click” tactile feedback to the finger204. An original encoder of the keyboard 302 may still work for key pushdetection, so no electrical connection is needed between the originalkeyboard side and the piezo actuator 702 side. In some illustrativeexamples, power and ground sources may be combined for circuits fromboth sides. Moreover, to simplify manufacturing, the base film 704 andthe flexible film 708 may be combined as part of a manufacturing andassembly process.

Example Keyboard Encoder

FIG. 9 illustrates a block diagram of a keyboard encoder 902 andactuator switches of a keyboard, such as the keyboard 302 of FIG. 3. Theencoder 902 is an example of an encoder, and any other encoder suitablefor use with actuator switches may be used. In the illustrated example,an actuator switch 904 has an electrode or other electrical connectionthat the encoder 902 detects when at least a minimum threshold amount ofpressure is applied to a key top of the actuator switch 904 to cause acircuit to close between a row R1 signal input 906 and a column C1signal input 908 of the encoder 902. The actuator switch may be anysuitable switch for use with the keyboard encoder 902, includingembodiments described herein, such as the actuator switch 100 of FIG. 1,the actuator switch 700 of FIG. 7, the actuator switch 1100 of FIG. 11,or the actuator switch 1400 of FIG. 14. Thus, multiple actuator switchesmay be used and integrated with the keyboard 302 by integrating eachactuator switch 904 with the encoder 902 and aligning each actuatorswitch 904 with a corresponding key top of a keyboard or keypad.

FIG. 10A illustrates a block diagram of the actuator switch 700. In theillustrative example, multiple actuator switches are used for thekeyboard, such as the keyboard 302, and each switch is connected to acommon base plane 712. In the example, the piezo actuator 702, the piezoelectrode 714 and the film electrode 706 for an example actuator switch700 are shown. In some illustrative examples, the same configuration maybe implemented for the actuator switch 100.

The piezo actuator 1102, the row electrode 1104, the column electrode1106, the film electrode 1112, the piezo electrode 1114 and the baseplane 1116 of FIG. 10B will be discussed in more detail below withrespect to FIGS. 11-13B. The piezo actuator 1402, the film electrode1404, the row electrode 1406, the column electrode 1408, the piezoelectrode 1412, the encoder electrode 1414 and the base plane 1416 ofFIG. 10C will be discussed in more detail below with respect to FIGS.14-15B.

Example Actuator Switch

FIG. 11 illustrates an exploded, perspective view of an example actuatorswitch 1100, with some aspects similar to the actuator switch 100 ofFIG. 1. In the illustrative example, the actuator switch 1100 usescapacitive switching and includes a piezo actuator 1102 for localizedhaptic feedback. A row electrode 1104 and a column electrode 1106 may beplaced between an upper flexible film 1108 and a lower flexible film1110. The row electrode 1104 and a column electrode 1106 may beinsulated from other electrodes. A film electrode 1112 is beneath theupper flexible film 1108 and may be open underneath in order to allowcontact with a piezo electrode 1114 when touch pressure is exerted onthe upper flexible film 1108 above the film electrode 1112.

In the illustrative example, the film electrode 1112 is connected to ahigh voltage signal source (HVP) and a base plane 1116 is connected toHVP's ground (HVG). The row electrode 1104 and the column electrode 1106may be connected to a corresponding position of an encoder, such as theencoder 902, in order for a keyboard to detect a key press. When atleast a minimum threshold amount of touch pressure is applied to theupper flexible film 1108 above the film electrode 1112 (e.g., pressing akey pad or area corresponding to a key with sufficient pressure to causethe film electrode 1112 to contact the piezo electrode 1114), the upperflexible film 1108 and the lower flexible film 1110 bend and the filmelectrode 1112 and the piezo electrode 1114 contact each other. Inresponse to the contact, the piezo actuator 1102 generates a “click”tactile feedback to the finger 204. Furthermore, a spacer 1118 islocated between the flexible film 1110 and the base plane 1116, similarto the spacer 112 of FIG. 1.

FIG. 12A illustrates a partial side, cross-sectional view of theactuator switch 1100 along section line A-A of FIG. 11, including theupper flexible film 1108 and the lower flexible film 1110 configured toflex in response to touch pressure. The spacer 1118 maintains a gap1202, similar to the spacer 112 of FIG. 1.

FIG. 12B illustrates a partial side, cross-sectional view of theactuator switch along section line A-A of FIG. 11 after touch pressureis applied to the upper flexible film 1108 and the lower flexible film1110 causing the film electrode 1112 to contact the piezo electrode1114.

Example Key Push Detection

FIG. 13A illustrates a block diagram for capacitive base key pushdetection for an actuator switch, such as the actuator switch 1100 ofFIG. 11. When pressure is not exerted above the film electrode 1112,such as in FIG. 12A, the row electrode 1104 and the column electrode1106 may each have a weak capacitive connection 1302 via the piezoelectrode 1114 because the piezo electrode 1114 is separated from therow electrode 1104 and the column electrode 1106 by the gap 1202 andthickness of the lower flexible film 1110.

FIG. 13B illustrates a block diagram for capacitive base key pushdetection. When at least a minimum threshold amount of touch pressure isexerted above the film electrode 1112, such as in FIG. 12B (e.g., when akey is pressed), the row electrode 1104 and the column electrode 1106may each have a stronger capacitive connection 1304 via the piezoelectrode 1114 because the gap 1202 no longer exists or is a minimallength. Thus, an encoder, such as the encoder 902, may detect the changein capacitance and may generate a key-push action (e.g., detects a keypress). FIG. 10B illustrates a block diagram of the actuator switch 1100that may be used for a keypad or keyboard, such as the keyboard 302.

Measured capacitance 614, as introduced regarding FIG. 6, above,provides an illustrative example of the change in capacitance duringkey-push and release for the actuator switch 1100. An eigenfrequency-based (“f0”) actuation signal is used for HVP, so that themeasured capacitance 614 is interfered from the signal. The filmelectrode 1112 and the piezo electrode 1114 may be excited by HVP, andthe “f0” component may feed into the measured capacitance 614 betweenthe row electrode 1104 and the column electrode 1106. This interferencemay become larger when the film electrode 1112 and the piezo electrode1114 are connected. Therefore, the “f0” component of the measuredcapacitance 614 can also be used for key-push detection. In someexamples, capacitance change due to a key push is slower than thecapacitance change due to the eigen frequency “f0,” so the “f0”component of the measured capacitance 614 can easily be separated byextracting the AC (or higher frequency) component from the measuredcapacitance 614. FIG. 6 also illustrates the AC component 616 of themeasured capacitance 614.

Example Actuator Switch

FIG. 14 illustrates an exploded, perspective view of an example actuatorswitch 1400, with some aspects similar to the actuator switch 100 ofFIG. 1. The actuator switch 1400 includes a piezo actuator 1402 forlocalized haptic feedback. The film electrode 1404, the row electrode1406 and the column electrode 1408 may be placed underneath the flexiblefilm 1410. A piezo electrode 1412 may be located on top of the piezoactuator 1402 and beneath the film electrode 1404 and a ring-shapedencoder electrode 1414 may be located on top of the piezo actuator 1402and beneath the row electrode 1406 and the column electrode 1408. Thus,the piezo electrode 1412 may be aligned with the film electrode 1404 andthe encoder electrode 1414 may be aligned with the row electrode 1406and the column electrode 1408. In the illustrative example, the filmelectrode 1404 is connected to a high voltage signal source (HVP) and abase plane 1416 is connected to HVP's ground (HVG). The row electrode1406 and the column electrode 1408 may be connected to a correspondingsignal input of an encoder, such as encoder 902, in order for a keyboardto detect a key press. Furthermore, a spacer 1418 is located between theflexible film 1410 and the base plane 1416, similar to the spacer 112 ofFIG. 1.

FIG. 15A illustrates a partial side, cross-sectional view of theactuator switch 1400 along section line A-A of FIG. 14, including aflexible film 1410 configured to flex in response to touch pressure. Thespacer 1418 maintains a gap 1502, similar to the spacer 112 of FIG. 1.FIG. 15B illustrates a partial side, cross-sectional view of theactuator switch 1400 along section line A-A of FIG. 14 after touchpressure is applied to the flexible film 1410. When at least a minimumthreshold amount of touch pressure is applied to the flexible film 1410above the film electrode 1404 (e.g., pressing a key pad or areacorresponding to a key with sufficient pressure to cause the filmelectrode 1404 to contact the piezo electrode 1412), the flexible film1410 bends and the film electrode 1404 and the piezo electrode 1412 maycontact each other. In response to the contact, the piezo actuator 1402may generate a “click” tactile feedback to the finger 204. Also, inresponse to at least a minimum threshold amount of touch pressureapplied to the flexible film 1410 above the film electrode 1404, the rowelectrode 1406 and the column electrode 1408 may contact the encoderelectrode 1414. The contact may cause the row electrode 1406 and thecolumn electrode 1408 to connect to each other via the encoder electrode1414, which may cause an encoder, such as the encoder 902, to detect akey-push action (e.g., detects a key press). FIG. 10C illustrates ablock diagram of the actuator switch 1400 that may be used for a keypador keyboard, such as the keyboard 302.

Measured voltage 618 as introduced regarding FIG. 6, above, provides anillustrative example of the change in voltage of the column electrode1408 during key-push and release for the actuator switch 1400. An eigenfrequency-based (“f0”) actuation signal may be used for HVP, so that themeasured voltage 618 of the column electrode 1408 may be interfered fromthe signal. The film electrode 1404 and the piezo electrode 1412 may beexcited by HVP, and the “f0” component feeds into the measured voltage618 via stray capacitance between the film electrode 1404 and the columnelectrode 1408, between the film electrode 1404 and the row electrode1406, and between the piezo electrode 1412 and the encoder electrode1414. This interference may become larger when the film electrode 1404and the piezo electrode 1412 are connected. Therefore, the “f0”component of the measured voltage 618 can also be used for key-pushdetection. In some examples, voltage change due to a key push is slowerthan the voltage change due to the eigen frequency “f0,” so the “f0”component of the measured voltage 618 can easily be separated byextracting the AC (or higher frequency) component from the measuredvoltage 618. FIG. 6 also illustrates the AC component 620 of themeasured voltage 618.

Example Keyboard

FIG. 16 illustrates an example keyboard 1600 including examples of oneor more of the actuator switches of the embodiments disclosed herein.The keyboard 1600 is an example of a keyboard that can be used with acomputer system, such the keyboard 302 of FIG. 3. A user, such as atypist, may rest his/her fingers 1602 on the keyboard 1600, such as whenhis/her fingers 1602 are in a home position familiar to trained typistsfor use in eyes-free typing. A key-press event may not be registereduntil a pressure on the top of a key 1604(1)-(N) meets or exceeds aminimum threshold pressure and is detected by a key-press sensingmechanism. Upon detecting or registering a key-press at a given key1604(1)-(N), a piezo actuator, such as the piezo actuator 102 of FIG. 1,may produce a tactile or haptic response to the key-press event. Asdescribed above with reference to the previous figures, this responsemay be localized to the specific key that was pressed upon such that theother fingers 1602 that are resting on the keyboard 1600 do not feel atactile sensation. That is, only the finger that pressed the key 1604may feel the tactile sensation caused by the force-producing mechanism.FIG. 6 shows that one of the fingers 600 of the user's right hand feelsthe haptic feedback after pressing upon that key (e.g., the “K” key)which registered a key-press. It is to be appreciated that the user maypress upon multiple keys 102(1)-(N) (e.g., SHIFT and “K”)simultaneously, or at the same time in sequence, which will causerespective haptic feedback to be felt by both fingers 1602 that pressedthe multiple keys.

Example Method

FIG. 17 is a flow diagram of an example process 1700 of providing hapticfeedback according to some implementations. The steps are performed byan actuator switch, such as the actuator switch 100 of FIG. 1. In someexamples, one or more of the steps are performed by one or more keys ofa keyboard or keypad, such as the keyboard 302. In some examples, thecomponents that provide an actuation signal when a key is pressed aremechanical components, and therefore do not include control logic, suchas logic devices and/or microcontrollers that detect which key/keyswitch is pressed in order to provide an actuation signal to acorresponding actuator.

At 1702, the surface of the flexible film 108 receives pressure. Forexample, a finger 204 applies pressure to the flexible film 108 abovethe film electrode 106. At 1704, if the pressure meets or exceeds aminimum threshold amount, then at 1706 a first electrode contacts asecond electrode. For example, the film electrode 106 contacts the piezoelectrode 104. At 404, if the pressure does not meet or exceed theminimum threshold amount, then the process returns to 1702. At 1708, theactuator switch 100 provides an input signal and generates, by a piezoactuator, haptic feedback. For example, the piezo actuator 104 deforms,causing haptic or tactile feedback for the finger 204.

The environment and individual elements described herein may of courseinclude many other logical, programmatic, and physical components, ofwhich those shown in the accompanying figures are merely examples thatare related to the discussion herein.

Other architectures may be used to implement the describedfunctionality, and are intended to be within the scope of thisdisclosure. Furthermore, although specific distributions ofresponsibilities are defined above for purposes of discussion, thevarious functions and responsibilities might be distributed and dividedin different ways, depending on circumstances.

CONCLUSION

In closing, although the various embodiments have been described inlanguage specific to structural features and/or methodological acts, itis to be understood that the subject matter defined in the appendedrepresentations is not necessarily limited to the specific features oracts described. Rather, the specific features and acts are disclosed asexample forms of implementing the claimed subject matter.

1. A keyboard comprising: a plurality of keys beneath a flexible film, each of the plurality of keys comprising: a first electrode underneath the flexible film, the first electrode coupled to a high voltage signal source; a second electrode located beneath the first electrode, the second electrode coupled to an input detector; a spacer configured to maintain at least a threshold distance between the first electrode and the second electrode when there is less than a first threshold amount of touch pressure applied to a top surface of the flexible film above the first electrode; a piezoelectric actuator beneath the second electrode, a top surface of the piezoelectric actuator coupled to the second electrode, wherein the piezoelectric actuator is configured to deform in response to contact between the first electrode and the second electrode; and a base plane beneath the piezoelectric actuator, the base plane coupled to a bottom surface of the piezoelectric actuator and a signal ground.
 2. The keyboard of claim 1, wherein the flexible film is configured to cause the first electrode to contact the second electrode in response to at least a second threshold amount of touch pressure applied to the top surface of the flexible film above the first electrode.
 3. The keyboard of claim 1, wherein the piezoelectric actuator is configured to provide haptic feedback in response to the first electrode contacting the second electrode.
 4. The keyboard of claim 1, each of the plurality of keys further comprising two additional electrodes underneath the flexible film.
 5. The keyboard of claim 1, wherein at least one of the plurality of keys comprises two additional electrodes configured to provide an input detection signal in response to a second threshold amount of touch pressure applied to the flexible film.
 6. An electronic device comprising: a flexible film; a first electrode underneath the flexible film, the first electrode coupled to a high voltage signal source; a second electrode located beneath the first electrode, the second electrode coupled to an input detector; a piezoelectric actuator beneath the second electrode, a top surface of the piezoelectric actuator coupled to the second electrode; and a base plane beneath the piezoelectric actuator, the base plane coupled to a bottom surface of the piezoelectric actuator and a signal ground.
 7. The electronic device of claim 6, wherein the flexible film is configured to cause the first electrode to contact the second electrode in response to at least a threshold amount of touch pressure applied to the flexible film.
 8. The electronic device of claim 6, wherein the piezoelectric actuator is configured to deform in response to the first electrode contacting the second electrode.
 9. The electronic device of claim 6, wherein the piezoelectric actuator is configured to provide tactile feedback in response to at least a threshold amount of touch pressure applied to the flexible film.
 10. The electronic device of claim 6, wherein a substrate is between the flexible film and the base plane.
 11. The electronic device of claim 6, further comprising two additional electrodes underneath the flexible film, each of the two additional electrodes configured to provide an input detection signal in response to a threshold amount of touch pressure applied to the flexible film.
 12. The electronic device of claim 6, further comprising two additional electrodes underneath the flexible film, each of the two additional electrodes, wherein the two additional electrodes are insulated from the first electrode and the second electrode.
 13. The electronic device of claim 6, wherein the second electrode is located at least a threshold distance beneath the first electrode when there is less than a threshold amount of touch pressure applied to the flexible film.
 14. A method of making an actuator switch, the actuator switch configured to: receive a threshold amount of pressure on a top surface of a flexible film; in response to receiving the threshold amount of pressure, contact a first electrode with a second electrode; and in response to the first electrode contacting the second electrode, generate, by a piezoelectric actuator, haptic feedback and provide, by a voltage signal source, an input detection signal.
 15. The method of claim 14, wherein the piezoelectric actuator deforms in response to a voltage from the voltage signal source applied to the piezoelectric actuator.
 16. The method of claim 14, wherein the first electrode is coupled to a high voltage signal source, the second electrode is coupled to an input detector, and the piezoelectric actuator is coupled to a signal ground.
 17. The method of claim 14, wherein a spacer maintains at least a threshold distance between the first electrode and the second electrode in the absence of touch pressure applied on the top surface of the flexible film above the first electrode.
 18. The method of claim 14, wherein providing the input detection signal comprises providing, by each of two additional electrodes, the input signal.
 19. The method of claim 14, wherein providing the input detection signal comprises providing, by each of two additional electrodes, the input signal, each of the two additional electrodes insulated from the first electrode and the second electrode.
 20. The method of claim 14, wherein providing the input detection signal comprises providing, by two additional electrodes, a capacitive-based input detection signal. 